Environmental news from California and beyond

NOAA greenhouse gas index climbs

November 10, 2011 | 1:28
pm

The U.S. National Oceanic and Atmospheric Administration released its Annual Greenhouse Gas Index (AGGI) number today, which measures the direct climate influence of a select set of greenhouse gases, and the news is not good. The numbers continue to climb, further evidence that the greenhouse effect is on the rise.

This comes on top of a staggering report released by the U.S. Department of Energy last week saying that global emissions of carbon dioxide –- a key, and long-lived, greenhouse gas –- had jumped by the biggest amount on record in the year 2010. The figures showed a 6% increase over the year before. That rise was steeper than worst-case scenarios that had been laid out by climate experts only four years before. That news was met with headlines worldwide calling it a “monster” increase and “the biggest ever seen.”

The Annual Greenhouse Gas Index number, by contrast, looks small, but has big impact. The index is a measure of the combined heating effect of the top greenhouse gases during their life spans as the gasses float around in the atmosphere. The number increased from 1.27 in 2009 to 1.29 in 2010, which is essentially a 2% increase. Since the index started in the Kyoto Protocol year of 1990, which the NOAA team chose as a baseline, the increase has been 29%.

“The way you have to look at these things is over time. So we’re up over 20% over where we were in 1990, in our effort to cut greenhouse gases. So we’re not doing very well,” says Jim Butler, director of the Global Monitoring Division of NOAA’s Earth System Research Laboratory in Boulder, Colo., which produces the Annual Greenhouse Gas Index.

Numbers on the Annual Greenhouse Gas Index, Butler points out, do not correlate directly to degrees difference in temperature. But when it goes up, warming potential increases.

“The sum of all of those tells you how much we’re increasing the warming potential of the atmosphere,” says Butler. “The analogy I use is the electric blanket. The numbers on the electric blanket don’t correlate to specific temperatures. If you’re really comfortable with it set on 3, and then you gradually turn it up to 6 to get warmer, at first you don’t notice anything. But in a little while you will, and then you’re going to stop turning it up, but you’re going to continue to get hotter.”

NOAA measures the gases in the atmosphere that most directly affect global warming, which it can do, Butler says, “with extreme accuracy.” The top five gases –- carbon dioxide, methane, nitrous oxide and two chlorofluorocarbons called CFC11 and CFC12 –- are responsible for more than 95% of the warming effect. About 15 other gases make up the last 5%.

Carbon dioxide is the biggest and baddest, as it is the longest-lived and most abundant. CO2 levels rose to an average of 389 parts per million in 2010, compared with 386 ppm in 2009. Back in the 1880s, before the Industrial Revolution, the CO2 concentration in the atmosphere was about 280 ppm. Other gases are showing similar increases.

One bit of good news in the report: Concentrations of CFCs 11 and 12 are dropping, albeit very slowly. Remember the ban on ozone-depleting aerosol spray propellants? It evidently works. The 1989 Montreal Protocol banned chlorofluorocarbons and they are gradually being reduced.

Perhaps this is an indication that another global protocol might have similar effects on greenhouse gases. Just an idea.

The Annual Greenhouse Gas Index is just a way to make unsexy science into a concept that people can easily grasp. The heat-trapping potential of a gas is called “radiative forcing” and is measured in watts per square meter. Who the heck knows what that means? Butler hopes the index makes it more clear.

“This looked like a good way of presenting much of what we do within our organization, so people can understand the real effects,” he says.